Development of a seismic damage evaluation method for embankments considering tensile failure of soil

(1)We研究了各向异性弹性常数的变化和滞后效应，在压力下-在循环荷载作用下，Ortiz模型需要进一步改进，建立本构模型需要积累土的脆性和延性特性的试验数据，反复荷载作用下土的裂纹数比反复荷载作用下的裂纹数多试验结果表明，对于等幅、空心圆柱扭转剪切试验，裂缝面积与剪切刚度之间有很强的相关性，且与剪切试验幅值和反复加载试验幅值的差异无关，拉性裂缝对土的强度和变形有很大的影响。（2）不同加载速率下高岭石粘土的劈裂拉伸试验表明，在加载速率较快时，土的抗拉强度较大。我们认为这种效应是由吸力引起的。(3)We对基于可液化土层的河堤变形进行了二维有限元分析。结果表明，现行的抗震评估方法可能高估了堤防在俯冲地震作用下的安全性，因此有必要引入累积损伤的概念。（4）基于断层破裂过程和场地效应的损伤评估方法对大面积地震的损伤评估是有效的。(5)We发展了基于移动质点半隐式法的变形分析方法，用于考虑拉伸破坏的路堤大变形计算。本文的方法可应用于具有可变形地面的微型模型的变形形状评价。

(1)We studied about the effect of the change and hysteresis of anisotropic elastic constants, on the stress-strain relationship and the crackThe Ortiz model should be improved in case of cyclic loading.Accumulation of experimental data on vulnerability and ductility characteristic of soil is necessary for the establishment of the constitutive model.The number of cracks of soil on the reversed loading tests is larger than in the case of the repeated loading tests, for equal amplitude, hollow-cylindrical torsional shear tests.The relationship between the area of crack and the shear stiffness is strong and is independent of the amplitude of shear test and the difference between the reversed and repeated loading test.The tensile crack has a strong influence on the strength and deformation of soil.(2)Tensile splitting tests of kaolinite clay for different loading rates, show that soil has a larger tensile strength during faster loading. We consider that this effect is induced by suction.(3)We performed 2 dimensional FEM analyses for liquefaction-induced deformation for river dikes based on liquefiable soil layers. The results show that the seismic evaluation by the current methods may overestimate the river dikes safety during a subduction earthquake, and therefore application of the cumulative damage concept is necessary for the seismic evaluation.(4)Our results suggest that the evaluation methodology based on fault rupture process and site effect is useful for the damage estimation of embankments spread over a wide area.(5)We developed the deformation analytical methodology based on the moving particle semi-implicit method for the large deformation estimation of embankment considering tensile failure. Our methodology may be applied for the evaluation of deformed shape of a miniature model with liquefiable ground.